Tuesday, October 30, 2012

Synovatron CVGT1 Eurorack-to-Buchla Converter

If you want to control a Buchla modular synthesizer with your Eurorack (or your Eurorack with a Buchla!) you should know that Buchla uses a different Volts-per-octave ratio as the Eurorack synthesizers, that work on a standard 1 Volts/Oct.
Buchla's pitch CV scaling conforms to neither the common 1V-per-octave or Volt-per-Hz (Roland) standards.

Buchlas generally conform to 1.2V/Octave (100mV/semitone) but older systems have 2V/octave scaling e.g. 258.
The other voltages lie in standard regions. 
Control voltages and timing pulses of the Buchla are +5V (signals with sustain) and +10V (transients only), and should be compatible with most other manufacturers' devices.
Besides that, Eurorack uses 3.5mm mini jack sockets and Buchla uses 4mm banana sockets.

Synovatron's latest module is a Eurorack format Eurorack/Buchla translator called CVGT1.
It was launched a few months ago at the Brighton Modular Meet at the University of Sussex just outside Brighton UK.
The 8 HP wide module allows Eurorack and Buchla synths to interact with each other, as the name suggest it provides a CV and a Gate/Trigger interface.

The module is an active module; The CV amplifiers use precision 0.1% resistors to set the scaling plus very fine adjustment by trim pots to achieve even better accuracy.
Trim pots (on the board) can be adjusted for trigger widths between 0.5ms and 5ms.
Not only does it provide the correct format connectors (and adheres to the Buchla color code) but it also deals with the CV scaling and offsetting and the gate/trigger and timing pulse conversion required to allow control in both directions.
CVGT1 can also be used to adapt to other banana connector synths e.g. Serge or Bugbrand which have 1V/octave using the "1" scale position.

More info at http://synovatron.blogspot.com

Watch the CVGT1 in action below (although it is hardly visible in the video, but i do like the soundscapes):

Video: Mutipatch 1 by Eldancer (Buchla and Eurorack)

mutipatch 1 from Eldancer on Vimeo.

Tony (from Synovatron) mailed me today that he can't make them fast enough, and that he's just over half way through my pre-order waiting list.
He underestimated the demand, initially he only bought enough components, pcbs and front panels for 20 modules (big mistake).
He will be building another ten or so but have negotiated with a local company to build the rest for him.